The proposal describes a study of the factors related to the onset of tobacco smoking. The school children in Muscatine, Iowa in grades 7, 8, 10, 11, and 12 will be the population investigated. Three main objectives will be pursued in the proposed project. (1) The primary objective is to conduct basic research into the correlates and explanation of adolescent smoking behavior. This will be done by developing and validating a method for the measurement of smoking behavior and then determining the "risk factors" or correlates of the onset of smoking and the development of smoking habit and testing a social learning theory of adolescent smoking. (2) The second objective is to develop an in-school smoking educational/prevention program guided in large part by our theory and findings from our research as well as by previous research and programs. The program will also be guided by the outcome of a pilot program currently underway. (3) Finally, we propose to conduct research to evaluate the short and longer term effectiveness of the program in preventing or delaying the onset of smoking among adolescents. Thus, we propose to approach smoking behavior through an integrated five-year sequence of research, prevention and evaluation. The project is an interdisciplinary effort of medicine, sociology and education involving medical, sociological and education personnel and techniques.